S46, S56, S66, RB75 +4X4

Phaser Engine Section 12A-06

Cylinder head assembly

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To change the valve springs (with cylinder head fitted)

Special tools:
Valve spring compressor, PD.6118B
Stud adaptor for use with PD.6118B, PD.6118-7 Setscrew adaptor for use with PD.6118B, PD.6118-8

Paragraphs 1 to 12 refer to a change of valve springs for a single cylinder.

1 Remove the rocker cover, operation 12A-01.

2 Turn the crankshaft in the normal direction of rotation until the inlet valve of the relevant cylinder has just opened and the exhaust valve has not fully closed. In this position the piston will be at approximately top dead centre (TDC).

3 Remove the rocker assembly, operation 12A-02.

4 Fit the valve spring compressor (Al) and the relevant adaptor (A2 or A3).

5 Compress the valve spring(s) and remove the collets. Ensure that the valve springs are compressed squarely or damage to the valve stem can occur.

6 Release the valve spring compressor and remove the valve spring caps and valve spring(s).
Attention: Do not turn the crankshaft while the valve springs are removed.

7 Put the new valve springs in position. If double valve springs are fitted, ensure that the closed damper coils are towards the cylinder head (12A.10/A).

8 Fit the valve spring caps.

9 Fit the valve spring compressor, compress the valve springs and fit the collets. Ensure that the valve springs are compressed squarely or damage can occur to the valve stem. Remove the valve spring compressor.

10 Fit the rocker assembly, operation 12A-02.

11 Check the valve tip clearances, operation 12A-05.

12 Fit the rocker cover, operation 12A-01.

If other or all of the valve springs are to be changed, they can be changed two cylinders at a time. The pairs of cylinders are: engine types AA, AB, AC and AD - 1 and 4, 2 and 3; engine types YA, YB, YC and YD - 1 and 6, 2 and 5, 3 and 4.

If the rocker assembly has been removed, piston TDC can be found as follows: Fit the valve spring compressor and compress the valve springs to open the valve. Turn the crankshaft, by hand, in the normal direction of rotation until the piston touches the valve. Continue to turn the crankshaft, and at the same time, release pressure on the valve spring compressor until the piston is at TDC (B).

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